Supervision circuit for telegraph systems



y 29, 1951 A. SNIJDERS 2,554,596

SUPERVISION CIRCUIT FOR TELEGRAPH SYSTEMS Filed Dec. 17, 1947 Patented May 29, 1951 UNITED STATES SUPERVISION CIRCUIT FOR TELEGRAPH TEMS Antonie Snijders, The Hague, Netherlands Application December 17, 1947, Serial No. 792,246 In the Netherlands September 14, 1946 Section 1, Public Law 690, August 8, 1946 Patent expires September 14, 1966 SYS 3 Claims.

The invention refers to a supervisory arrangement for a teleprinter communication system.

The object of the invention is to provide a receiving arrangement responsive to a signal consisting of a mark start element followed by five mark elements. Ordinarily teleprinters are not responsive to this five-mark-signal.

Conversely, the arrangement of the present invention is not responsive to the signals which actuate the teleprinter.

For selective separation the arrangement according to the invention comprises a group of a condenser and a high ohmic leak resistance as a timing device. The leak resistance is shunted by a diode causing the timing device to act slowly for one current direction, but rapidly for the opposite direction of the current.

The voltage across the condenser serves as a bias for a three-electrode vacuum tube, the terminals of the condenser being connected to the cathode and the grid, respectively.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

The only figure is a wiring diagram of an arrangement according to the invention.

Referring to the drawing, a telegraph battery has its midpoints grounded and is bridged by two potentiometer resistances R3 and R4, the junction of the resistances R3 and R4 being formed by a point Z. Point Z is connected to a high ohmic resistance RI and the cathode of a diode D which bridges the resistance RI by having its anode connected to a point Y being the junction of resistance RI and a condenser Cl the other side of which is formed by a point X connected to the cathode of a three-electrode vacuum tube B. The grid of tube B is connected by a resistance R2 to the point Y and the anode of diode D. Point X is connected to the armature a of a signal reception relay A. Armature a moves between two stationary contacts connected, respectively, to the positive and negative battery terminals. In the anode circuit of tube B is inserted a supervisory relay AR, having two armatures m and ar Armature ar is connected to the negative battery terminal over a resistance R5 and a switch S which may be hand-operated, and the contact with which ar cooperates is connected to the terminal of relay AR which is connected to the anode of tube B. Armature a1" is connected in series between the negative battery terminal of a supervisory circuit SC the other terminal of which is connected to the positive battery terminal.

The operation of this device is as follows:

The condenser C1 and the resistance R1 are connected in series and form a time delay circuit for tube B, resistance R1 being shunted by the diode D. The operation of tube B depends on the voltage diiierence between the points X and Y. In the position shown in the drawing, the relay armature a, which is controlled by the signal reception relay A, connects point X to the positive battery terminal e. g. to volts. Point Y has the same potential as point Z, which is determined by the values of potentiometer resistances R3 and R4, and is negative with respect to the potential of point X. For instance, point Y may have a potential of 20 volts, i. e. volts less than the potential of point X.

When a signal arrives, the start element causes relay armature a to reverse, and the potential of point X is shifted by 120 volts from 60 to 60 volts.

At first point Y tries to follow the change of voltage of 120 volts, i. e. its voltage is changed to a value near -140 volts, but at once a leaking current begins to flow through resistance R1, which restores the potential of Y to the initial value of -20 volts. The diode D is in blocking position for this current direction.

While changing its potential from approximately 140 volts to -20 volts point Y passes the potential 60 volts of point X, and from this moment onwards the grid of tube B ispositive with respect to the cathode. The time delay with which this happens can be adjusted very accurately, much more accurately than it could be achieved with an arrangement based on the end value of the condenser voltage which is only reached asymptotically.

This enhanced accuracy is useful as will be clear from considering that, when utilized for the normal five-unit code, the tube B must not become conductive before milliseconds, and not later than milliseconds after the beginning of the start element. In practice the margin between these tolerances is reduced to a much narrower interval, owing to various technical deviations from the theoretical value which are unimportant for the present disclosure.

It is an important advantage of the present invention over other arrangements proposed for similar purposes, that the accuracy of the arrangement is widely independent of battery volt age.

The potentiometer resistances R3 and R; can be equal to each other so that point Z assumes ground potential without being grounded directly.

Direct grounding of point Z, without provid- 60 1113 the potentiometer resistances R3 and R4, is

theoretically possible but is not preferred, because the time delay in operation of the tube B is in such an arrangement dependent on the battery voltage and on the symmetry of the battery.

Any of the signals to which the teleprinter is responsive, comprises at least one space ele-. ment within 100 milliseconds after the start. This element causes the armature a to move back to the positive battery voltage, making the potential of point X+60 volts. The voltage between points Y and Z changes its size and the diode D becomes conductive, making the potential.

of point Y rapidly equal to the potential of point. Z. The term diode i understood to include vacuum tube diodes, rectifier cells, resistors the resistance value of which depends on the temperature, and the like.

The arrangement is now prepared for the next signal.

The five-mark signal to which the described arrangement responds is not used for the teleprinter, because otherwise every line current interruption would be printed.

The tube B becomes conductive when 100 milliseconds after the start element the fifth mark arrives. The anode current energizes the supervisory relay AR, having an armature are to actuuate a monitor or supervisory circuit SC. Holding armature cm keeps thereby AR in operation even if tube B should become non-conductive again by the stop element of the signal. Relay AR can be restored to normal by interrupting the holding circuit by the switch S.

The supervisory circuit SC can serve for any convenient purpose which has no relation to the invention proper. For example it may start a visual and/or audible alarm (not shown), call a receiver for special messages (e. g. time signals transmitted in five-unit code), give a closing signal, etc.

The battery shown in the drawing can be the same as that serving the teleprinters. For that purpose its midpoint is grounded, but for the present invention the ground connection is. not essential. With a common battery serving both the teleprinter and the above described device, relay A. and its armature a may also be utilized for both these purposes. For this reason the normal or space position is shown in the draw.- ing with positive battery voltage on the armature a, in accordance with standard teleprinter practice. The resistances R2 and B5. protect the tube 13 against excessive amperages.

It will be understood that each of the elements described above, or two or more together, may also find a useful applicationin other types of devices for receiving special signals diiiering from the types described above.

While I have illustrated and described the invention as embodied in a device for receiving special signals in a teleprinter code, I do not intend to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of my invention.

Without further analysis, the foregoing, will so fully reveal the gist of my invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics or the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended'within the meaning and range of equivalence of the following claims.

1. A device for receiving special signals in a teleprinter code, comprising in combination, a D. C. source; means for defining a point having athird potential between the terminal potentials of said D. C. source; a receiving relay having a movable armature; two stationary contacts cooperating with said armature and being connected, respectively, with the terminals of said D. C. source; a condenser and a high ohmic resistance connected in series between said armatureoi'. saidreceiving relay and said point having a third potential; a diode connected in shunt tosaidhigh ohmic resistance; a vacuum tube having at least an anode, a cathode and a grid, said cathode and said grid being connected, respectively; to the terminals of said condenser; a supervisory relay connected in the anode circuit of said vacuum tube and having an armature; and a supervisory circuit controlled by said armature of said supervisory relay.

2. A device for receiving special signals in a teleprinter code, comprising in combination,v a D. C. source; a potentiometer connected across said D. C. source and having a tap; a receiving.

relay having a movable armature; two stationary contacts cooperating with said armature and be-' ing connected, respectively, with the terminals of said D. C. source; a condenser and'a'higlr ohmic resistance connected in series between said armature of said receiving relay and said tapof said potentiometer; a diode connected in shunt.

to said high ohmic resistance; a vacuum tube having at least'an anode, a cathode and a grid,

said cathode and said grid being connected, re-

spectively, to the terminals of said condenser; a.

supervisory relay connected inthe anode circuit of said vacuum tubeand havingan armature; anda supervisory circuit controlledby said armature of said supervisory relay.

3. A device for receiving special signals in. a

teleprinter. code, comprising in combination, a. D. C. source; means for defining a point having.

a third potential between the terminal. potentials of said D. C. source; a receiving relay having a movable armature; two stationary contacts cooperating with said armature and. being connected, respectively, with oppositev current source potentials; a vacuum tube having a cathode, a.

tube; a diode connected in shunt to said highohmic resistance; a supervisory relay connected in the anode circuit of said vacuum tube and having an armature; and a supervisory circuit controlled by said armature of said supervisory relay.

ANTONIE SNIJDERSL REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,094,733 Byrnes Oct. 5, 1937 2,442,427

Mullerheim June 1, 19485 

